Mobile devices can be configured to function as radio frequency identification (RFID) device transponders utilizing near field communication (NFC). So configured, the mobile devices can be used as transponders in contactless card systems to communicate with a reader device. For example, a mobile phone can be used to communicate payment information or authorization credentials over NFC.
Typically, RFID devices utilizing NFC are configured for either passive load modulation (PLM) or active load modulation (ALM). While, ALM is typically more complex than PLM, components for implementing ALM in a transponder (e.g., a mobile device) are more compact and, because the transponder utilizes a power source to generate a magnetic field rather than just modulate a magnetic field created by a reader, an ALM transponder has a greater signal range than a PLM transponder. Small components able to produce a signal with a large signal range are often advantageous to the design and function of a mobile device configured to function as an ALM transponder.